Remote control and alarm system for a compressor station and compressor engines thereof



May 7, 1963 Filed Aug. 1, 1960 CONTROL c. E. MILLER 3,088,655 REMOTE CONTROL AND ALARM SYSTEM FOR A COMPRESSOR STATION AND COMPRESSOR ENGINES THEREOF '2 Sheets-Sheet 1 TO OTHER CYLINDERS FIG.

INVENTOR.

CLARENCE E. MILLER BY MAHONEY MILLER & RAMBQ ATTYS. MA 7 Y May 7, 1963 C. E. MILLER REMOTE CONTROL AND ALARM SYSTEM FOR A COMPRESSOR STATION AND COMPRESSOR ENGINES THEREOF Filed Aug. 1, 1960 2 Sheets-Sheet 2 United States Patent 3,088,655 REMOTE CONTROL AND ALARM SYSTEM FOR A CGMPRESSOR STATION AND COMPRESSGR EN- GINES TIIEREGF Clarence E. Miller, Lancaster, Ohio, assignor to The Ohio Fuel Gas Company, Columbus, Ohio, a corporation of Ohio Filed Aug. 1, 1960, Ser. No. 46,795 Claims. (Cl. 230-2) My invention rel-ates to a remote control and alarm system for a compressor station and compressor engines thereof. It has to do, more particularly, with an automatic system which, for example, is applied to a gas compressing and pumping station of the type employed for compressing and pumping natural gas. These stations usually include a number of high-capacity compressors which are operated by large internal combustion engines usually of the reciprocating type employing natural gas as the fuel.

It is desirable that these stations be maintained automatically from a remote location to save manpower and because they are often in relatively remote or inaccessible locations. The system of the present invention will indicate at a supervisory control point normal operating conditions. In case of various malfunctions at the station, an alarm will be given at supervisory control and certain shutdown operations will automatically occur. The system will distinguish between those malfunctions which affect the entire station and those which affect the individual compressor units of the station. In the case of the former, the entire station will be shut down but in the case of the latter, only the individual faulty compressor unit which is not functioning properly will be shut down.

In the accompanying drawings, I have indicated a system embodying my invention applied to a compressor station having a number of compressor units, each of which includes a plurality of compressors and a driving internal combustion engine.

In these drawings:

FIGURE 1 is a schematic illustration of the entire system.

FIGURE 2 is a schematic illustration of a type of pressure-actuated mercury switch used in the system.

FIGURE 3 is a schematic view of the electrical system only 'and which shows all the elements in deenergized condition.

The system which I have provided is mainly an electrical system including switches or relays which are in circuit with various controls at the station and at the individual compressor units thereof to indicate normal operation or to indicate malfunctions and to automatically shut down the entire station or any faulty compressor unit thereof. The switches preferably are actuated directly by fluid pressure from various units to be controlled in which pressure conditions vary or by fluid pressure resulting from changes in temperature conditions in various units to be controlled, although direct electrical connections could be used in some instances.

The station building is preferably equipped with firedetection devices which are connected in the system of this invention. These are so connected in the electrical circuit of the system that in case of fire, the circuit is broken to close down the entire station, and an alarm is given at supervisory control. The station includes a suction header through which the gas is conducted to the various compressor units and a discharge header into which the gas compressed by the various compressor units is discharged. It also includes an air supply header which supplies control air for the entire system plus starting air to the various compressor engines for turning them over in the starting operation. The first two headers are connected by fluid pressure lines to various switches connect ed in the main circuit so that upon the occurrence of abnormal pressure conditions in any of the headers the main circuit of the system is broken to shut down the entire station and to signal supervisory control. The supply header is connected by a fluid pressure line to a switch connected in the main circuit so that when the pressure therein drops below a predetermined minimum a signal is given at supervisory control so that, if necessary, after a predetermined period, steps can be taken to restore the pressure in such air supply header.

As indicated above, in connection with the compressor units, each individual engine which drives its associated compressor or compressors is controlled by the system in such a manner that only the individual faulty engine is shut down in case of malfunction of that compressor unit. Thus, various sub-units of each compressor unit are provided with controls which function in accordance with varying pressure or temperature conditions to break the electrical control circuit for the engine of that particular compressor unit to shut down that engine and to provide a signal to indicate the fault causing the engine to shut down. For example, these conditions may be high jacket water temperature, low oil pressure, overspeed, low jacket Water pressure, high gas discharge temperatures in the respective stages thereof, high starting air temperature, high interstage gas pressure, excessive vibration of the engine and compressor, or overheating of any of the cylin ders of the engine.

The system of this invention is so designed that any number of controls may be removed or added, in the entire station shutdown or individual compressor unit shut down portions of the system.

The drawings show component parts of the system arranged and connected to protect the station and the individual compressor units thereof in case of malfunction due to various pressures, temperatures and overspeed conditions as indicated above. A fail-safe system is provided by arranging the safety controls and relay coils in series in the electrical control circuit. Thus, any break in continuity of a particular section of the safety control circuit will deenergize the associated relay coil. It is preferred to use mercury tube switches in the control circuit which are of the semi-automatic, hand reset type. By using this type of mercury switch containing a single pole double throw mercury tube, the associated relay coil can be conneoted through the normally closed contacts at the lower end of each tube to maintain constant continuity of the circuit to the relay coil. When a malfunction occurs, the mercury tube connected to the control that is affected by that function, tips to break continuity to the associated relay coil, thus shutting down the entire station or the individual compressor unit. At the same time that mercury tube also makes contact through the mercury which moves to its opposite end to complete a circuit to a pilot light that indicates the malfunction. The tube of the switch will stay in this tipped position until reset by hand. The pilot light remaining on will indicate to supervisory control or to the operator when he returns to the station, what malfunction has occurred at the station to cause complete shutdown of the station or shutdown of the engine of an individual compressor unit.

With reference to FIGURE 1, I have indicated diagrammatically the functions of the station and of each individual compressor unit thereof to be controlled. I have shown only one compressor unit schematically but it is to be understood that any desired number may be provided in the station. The circuit diagram of FIGURE 3 will aid in understanding the electrical connections. The power supply for the circuit is preferably batteries so as to have a constant electric supply.

The station building may be equipped, for example above the compressor units, with a fire detection set in the form of bimetallic contactors T and connecting wire. The bimetallic contactors are connected in series across the power lines with the coil of a control relay CR1. The contacts CR1 of the relay CR1 are connected across the power lines in series with a signal pilot light 1. The bimetallic contactors T provide normally-closed contacts which make a circuit to the CR1 relay coil. They may be set to open at a suitable temperature. As long as the relay coil of the relay CR1 is energized the contacts CR1 of relay CR1 are open and the circuit to the pilot light 1 is broken and the light out signals normal operation of the fire-detection set.

The station is also equipped with a station suction header S as indicated in FIGURE 1 which is a conduit that connects the gas supply line entering the station to the various compressor units, only one of which is shown in the figure, the particular way in which the connection is made to the inlet of the compressor not being shown as this is not important. Connected to this header is a control pressure tube 20 which controls a mercury switch A of a particular type shown in FIGURE 2.

This switch A is of a standard single pole double throw type readily available and includes a curved pressure tube 21 which is connected to the tube 20 for receiving pressure therefrom which controls tilting of a mercury tube 22 which has a pair of contacts at each end connected in the circuit. When a reduction in pressure occurs in the curved tube 21, it tends to contract to a shorter radius and the mercury tube 22 is tilted to break the circuit to relay CR2 with which it is connected. The switch A is actuated to open the circuit when the suction pressure in the header S drops below a predetermined amount. The switch can be reset by a pushbutton arrangement which is not shown. As will be apparent later, other equivalent switches are provided in the system and are selectively arranged to open the circuits upon a rise in pressure or a drop in pressure in the units which they control. When there is a rise in pressure the curved tube tends to straighten out.

The switch A is connected across the power lines in series with the coil of a second relay CR2 and between this switch and this coil is another set of contacts CR1 of the relay CR1 which are closed to energize relay coil CR2 when relay coil CR1 isenergized. The relay CR2 also includes the normally closed contacts CR2 which, when the relay coil CR2 is energized, will open and give a light out signal to supervisory control of normal operation.

The station is also equipped with a station discharge header U which is connected to the discharge side of the various compressor units of the station, the actual connection not being shown. The gas compressed by the various compressor units is discharged into this header. Switches B and C, like the switch A, are con trolled by the variation in pressure in this header and are connected thereto by the control pressure tube 23. The switch -B will be set to open the circuit upon the occurrence of a low discharge pressure in the header U whereas the switch C will be set to open the circuit upon the occurrence of a high discharge pressure in the header U. The switch B and the switch C are each connected across the power lines in series with the relay coil CR2 and are normallyopen relay contacts CRl which control the relay coil CR2. Thus,'when all of the switches A, B and C and the contacts CRI are closed, the'coil of relay CR2 is energized and opens the normally closed contacts CR2 thereof to give a light out signal to supervisory control that normal conditions are present in the headers S and U and the tire detection system.

Each of the switches A, B and C are connected in series with the respective pilot lights 2, 3 and 4, so that asignal is alsogiven at the station when there is a malfunction in the headers S and U, and in which the trouble is located, by which the switches are controlled. Then when the station operator returns, he knows in which header the difficulty occurred.

An air supply header V is also provided at the station for supplying control air and starting air for the engines of the compressor units of the station. The connectors of this header to these engines are not shown as they are not important to describing the present invention. These engines may be equipped with suitable starting and stopping systems using control air and starting air, for example, like the system disclosed in the patent to King No. 2,9!3Il,l66, dated April 5, 1960.

A switch D, like the switches A, B and C, is controlled by variation in pressure in the header V through the medium of a control pressure tube 24. This switch controls a signal circuit to supervisory control. When the pressure in the header V drops below a safe pressure, the mercury switch D completes the signal circuit to supervisory control and gives a signal, such as turning a pilot light on, at the remote supervisory control location. This circuit does not shut the engines down but operates a signal only because the air pressure may build up itself and correct this fault. However, if it does not correct itself, steps can be taken at supervisory control.

The controls which operate to shut down the entire station or to indicate trouble affecting the entire station have been described above. As previously indicated, further controls are provided on each compressor unit in the station for indicating malfunction of each unit and/ or shutting down that particular unit. The controls disclosed below are for one compressor unit comprising a plurality of compressors and will be duplicated on each compressor unit provided in the station. The control switches are the same type as the mercury switches previously mentioned.

A switch E is provided in the circuit and is actuated by high jacket water temperature through the control tube 25 which is connected to the outlet of the water jacket of the compressor engine and which is filled with gas affected by the temperature of the water in the pocket. A similar switch F is provided and is controlled through a control tube 26 which is connected to the lubricating system of the engine to be actuated by low oil pressure therein. A switch G is actuated through a pressure tube 27 which isconnected to the governor of the engine. The governor is of the pressure type and will build up pressure in the tube 27 upon overspeed to actuate the switch G. A switch H is actuated through a tube 28 which is connected to the inlet of the water jacket of the engine and actuated by low jacket water pressure.

A switch J is provided for actuation by high gas discharge temperature and is connected by a tube 29 to the discharge side of the compressor. The tube will be sealed and contain a supply of gas or other fluid which will be expanded by the temperature of the gas discharged from a certain compressor to actuate the switch I when a predetermined temperature is reached at the discharge of that compressor. Similarly, switches K, L and M are connected by the control tubes 30, 31 and 32, respectively, to the other compressors of the unit.

A control is provided which is actuated by high starting air temperature and includes the switch N. This high starting air temperature may be created by a back-up of flame through the starting air valve to which the starting air line is connected. The switch N is controlled through a tube 33 which is filled withgas affected by the temperature in the starting air line. Thus, the switch N will be opened upon the occurrence of a high temperature in the starting air line leading into the engine.

An additional control is provided on the interstage header I which is connected in the usual manner, not shown, to the various compressors. This control includes the switch P which is connected by a control tube 34 t0 the header I so that the switch will open upon development of high interstage pressure in the header 1.

All the switches E, F, G, H, I, K, L, M, N, and P are connected across the power lines in series with each other and with the normally-closed contacts 18A, the normally closed relay contacts CR4 the normally opened contacts CR2 of the relay CR2, and the coil of the relay CR3. The contacts 18A are in a vibration switch of the lock-in manually reset type which is mounted on the engine to be affected .by excessive vibration thereof indicating a malfunction. The switch also includes contacts 18B which are normally open and which are connected across the power lines in series with a pilot light 15.

Thus, all of the switches E, F, G, H, J, K, L, M, N, and P and the contacts 18A, the relay contacts CR4 and the relay contacts CR2 control energization and deenergization of the relay coil CR3. Whenever all of these switches and contacts are closed, the relay coil is energized and when any switches or contacts are open, the coil is deenergized. The pilot light 15 will be actuated by closing of the contacts 13B to indicate to the station operator that there has been excessive vibration of the engine. Pilot lights 5, 6, 7, 8, 9, 10, 11, 12, 13 and 14 are connected in series, respectively, with the switches E, F, G, H, J, K, L, M, N, and P so that when each switch is closed, due to the mercury tube tilting to its malfunction position, indicating a malfunction of the compressor unit, the respective pilot light is turned on indicating to the station operator when he returns, the location of the malfunction in the compressor unit.

The control circuit also includes the normally open contacts CR4 of a relay CR4 which are connected across the power lines in series with a pilot light 16. It also includes a power cylinder overheat pyrometer O of the lock-in manual reset type which is associated with each of the cylinders of the compressor driving engine which is indicated as an eight cylinder engine. Each pyrometer is connected to a thermocouple (not shown) in the exhaust of the cylinder. These pyrometers are in parallel and are connected in series with the coil of the relay CR4 across the power lines. The circuit further includes an engine shutdown control in the form of the shutdown solenoid valve SV2 which is connected across the power lines in series with the normally open contacts CR3 of the relay CR3. The valve SV2 will, when deenergized, shut down the engine by interrupting the supply of air to the pneumatic starting and stopping system and bleeding down such system. This valve may be used in place of the valve 31 referred to in Patent No. 2,931,166. If the valve SV2 is used in place of the valve 31 and it is desirable to control valve 31 remotely, then a set of contacts would be required in series with the coil of SV2. However, the solenoid SVZ may shut down the engine in other Ways. The relay CR3 includes another pair of normally closed contacts CR3 which are connected across the power lines in series with a pilot light 17 or engine shutdown alarm. Also, another set of normally closed contacts CR3 are provided in the relay CR3 and control a circuit to supvervisory control to indicate when an engine shutdown occurs.

A pilot lamp test circuit is connected to each pilot lamp 1 to 17, inclusive, and the test circuit for each is controlled by a pair of normally open contacts 19 connected in series with each lamp. These contacts are carried on master or gang switches. It is preferred to use two gang switches, one for testing the station pilot lights 1 to 4 and the other for testing the compressor pilot lights 5 to 17 but other arrangements may be provided.

Normal Operation For normal operation when the system is energized by sending power into the power lines, the fire detection unit, mounted in the station building above the engines, has the contacts of the bimetallic contactors T normally closed which complete a circuit to the CR1 relay coil.

This causes the CR1, normally closed contacts to open so that the pilot light 1 is out indicating that the fire detection unit is in normal condition. At the same time CRI normally open contacts will close and complete the circuit from the station mercury tubes A, B and C to the coil of the relay CR2. The CR2 normally closed contacts will open, breaking the circuit to supervisory control to turn out a pilot light at a remote location so as to indicate normal conditions in headers S, U and the fire-detection system. The normally open contacts CR2- will close to complete the circuit from the mercury tubes E, F, G, H, J, K, L, M, N and P, for each engine in the station, and the circuit will include the normally closed contacts 18A and the normally closed CR4 relay contacts from the cylinder overheat pyrometers to the coil of the CR3 relay. The normally open contacts CR3 of relay CR3 will close completing a circuit to solenoid valve SV2 that must be energized to keep the pneumatic system of the engine in operation. The normally closed contacts CR3 of the relay CR3 will open to deenergize the signal or pilot light 17 showing that the compressor engine is operating properly. The other normally closed relay contacts CR3 will open and break the circuit to supervisory control so that the shutdown pilot light there will be ofi to indicate normal operation of the engine. With no overheat condition existing in any of the engine cylinders, the pyrometers 0 will break the circuit to the CR4 relay coil so that it is deenergized, and thus the normally open relay contacts CR4 will cause the pilot light 16 to be off indicating normal operation of the engine in regard to cylinder exhaust temperature, and the CR4 normally closed contacts will be a part of the closed circuit to the coil of the relay CR3. Vibration switch normally open contacts 18B will at this time break the circuit to the pilot light 15 indicating normal operation of the engine in this respect.

Malfunction Operation Station malfunclion.ln case of malfunctions which effect the station as a whole all the engines in the station will shut down. These station malfunctions may be fires detected by any bimetallic contactor T or abnormal conditions in the headers S and U.

If fire breaks out and is detected by any bimetallic con tactor T, the CR1 relay coil is deenergized. This closes the CR1 contacts to complete a circuit to the light 1 to indicate fire to the operator in the station. This light would also indicate any other break in the circuit. The other set of CR1 contacts CR1 i opened and thereby deenergizes the relay coil CR2. This closes the relay contacts CR2; which completes the circuit to a pilot light at supervisory control to indicate shutdown of the entire station. The other set of CR2 contacts CR2 is opened and this breaks the circuit to the relay coil CR3, causing the one set of CR3 relay contacts CR3 to open and deenergize the valve SVZ and shut down the engine. The second set of CR3 contacts CR3 close and energize the alarm 17 to give an alarm or indication to the station operator when he returns of the shutdown of the engine. The third set of contacts CR3 of the relay CR3 are closed to complete the circuit to supervisory control to light the pilot light thereof to indicate engine shutdown.

Each engine of the station has a set of CR2 relay contacts controlled by the coil of the CR2 station shutdown relay. Therefore, when the CR2 relay coil is deenergized all engines of the station are shut down.

When any of the switches A, B or C opens to break the circuit which it controls, the respective pilot lights 2, 3, or 4 indicates to the station operator Where the fault is, that is, in the respective headers S and U. The switch A functions to indicate low suction pressure, the switch B to indicate lo-w discharge pressure, and the switch C to indicate high discharge pressure. This will cause all engines to shut down since the relay coil CR2 is deenergized and the contacts CR2 of each engine which are 7 connected to the coil CR will deenergize that coil and open the contacts CR3 which are connected to the control valve SV2 of each engine, as described above with reference to the fire detection. Operation of the switch D does not shut down the station, as previously indicated, but only closes a circuit to supervisory control to give a signal of abnormal conditions in the air supply header V.

Individual engine malfunctin.In case of malfunctions which affect only an individual engine, only that engine is shut down and a pilot light is energized to indicate to the station operator the fault which caused the shutdown.

Thus, for example, if any of the mercury tube switches tips from its normal position for reasons indicated below the indicated pilot light is turned on to show the fault causing the engine to shut down.

Mercury switch: Pilot light When any of the mercury tube switches listed above tips from its normal position, when the vibration switch contacts 18A open because of excessive vibration of the engine, when the cylinder overheat contacts CR4 open because of energization of the CR4 relay coil by the power cylinder pyrometers O, the circuit to the CR3 relay coil is broken. This will operate the valve SV2 to shut down the individual engine. When excess vibration causes the switch contacts 18A to open and 1813 to close, the contacts 18A shut down the engine as indicated and the contacts 1813 complete a circuit to the pilot light to indicate to the operator excessive vibration of the engine.

If one of the engine cylinders overheats and actuates a 'pyrometer, a circuit is made to the CR4 relay coil. When this coil is energized, the CR4 relay contacts are closed and the pilot light 16 is turned on indicating to the operator that there is an overheated cylinder. This also opens the other relay contacts 0114 to deenergize the relay coil CR3, which opens the relay contacts CR3 that control the valve SV2 and, thereby shuts down the engine.

It will be apparent from the above that I have provided a control system for a gas pumping or compressing station which may have one or more enginedriven compressor units. Each driving engine for each compressor unit is provided with an engine shutdown control SV2 which is controlled by an electric circuit. This circuit includes an engine shutdown relay CR3 which has a set of contacts in series with the engine shutdown control SV2. The coil of the engine shutdown relay CR3 is connected in series with the contacts of other relays CR2 and CR4, which operate upon malfunction of station units and various sub-units of the compressor unit, respectively. The coil of the engine shutdown relay CR3 is further controlled by contacts of station shutdown relay CR2, which operates upon the occurrence of various station malfunctions as distinguished from individual engine malfunctions, and the relay CR2 is controlled by the contacts of relay CR1 in accordance with the condition of the firedetection system. The safety controls and the engine shutdown relay coil CR3 are arranged in series to give a fail-safe system, since any break in continuity will deenergize the relay coil. For each malfunction, either station or engine, a pilot light is turned on at the station to indicate to the operator when he returns where the malfunction occurred. Also, for each station shutdown or individual engine shutdown, a pilot light or signal is actuated at supervisory control to indicate individual engine shutdown or station shutdown.

Thus, I provide a remote control and alarm station which is an automatic system that is particularly applicable to a gas com-pressing and pumping station of the type employed for compressing and pumping natural gas. Many of the advantages of this system have been discussed above and others will be apparent.

According to the provisions of the patent statutes, the principles of this invention have been explained and have been illustrated and described in what is now considered to represent the best embodiment. However, it is to be understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically illustrated and described.

Having thus described my invention, what I claim is:

1. In combination with a compressor station having a plurality of independent compressor units, each of which includes a'driving engine having a shutdown control, said station including a plurality of normally functioning station elements, each of said compressor units including a plurality of normally functioning compressor elements; an automatic control system connected to all of said station and compressor elements and including a first control section connected independently between said station elements and the shutdown control of each of said compressor driving engines and actuated by each of said station elements upon a malfunction thereof to shut down all of said compressor units and a second control section connected between all of said compressor elements of each compressor unit and the shutdown control of the engine thereof to shut down only the engine thereof upon the malfunction of any of said compressor elements.

2. In combination with a compressor station having a plurality of independent compressor units, each of which includes a driving engine having an electrically actuated shutdown control, said station including a plurality of normally functioning station elements, each of said compressor 'units including a plurality of normally functioning compressor elements; an automatic control system connected to all of said station and compressor elements and including an electric circuit having a first control section connected independently between said station elements and the shutdown control of each of said compressor driving engines and having a control actuated by each of said station elements upon a malfunction thereof to actuate the shutdown control to shut down all of said compressor units, the controls actuated by the various station elements being connected to the shutdown control in parallel relative to each other, said circuit also including a second control section connected between all of said compressor elements of each compressor unit and the shutdown control of the engine thereof to actuate the shutdown control to shut down only such engine upon the malfunction of each of said compressor elements, said second control section comprising a control actuated independently by each of said compressor elements upon a malfunction thereof, the controls actuated by the various elements of each compressor unit being connected to the shutdown control of such unit in parallel relative to each other.

3. In combination with a compressor'station having a plurality 'of independent compressor units, each of which includes a driving engine having an electrically actuated shutdown control, said station including a plurality of normally functioning station elements, each of said compressor units including a plurality of normally functioning compressor elements, an automatic control system connected to all of said station and compressor elements and including an electric circuit having a first control section connected independently between said station elements and the shutdown control of each of said compressor driving engines and actuated by each of said station elements upon a malfunction thereof to shut down all of said compressor units and a second control section connected between said compressor elements of each compressor unit and the shutdown control of the engine thereof to shut down only the engine thereof upon the malfunction of any of said compressor elements, said first control section of the circuit comprising a station shutdown relay having a coil connected in series with contacts actuated by said station elements, said second control section of the circuit having an engine shutdown relay with contacts connected in series with said engine shutdown control and having a coil connected in series with contacts of said station shut down relay, said second control section of the circuit also including contacts actuated by said compressor elements which are connected in series with said coil of the engine shutdown relay.

4. The combination of claim 3 in which said first control section of the circuit includes contacts actuated by 10 an additional station element, said contacts being connected in series with the coil of a relay which has contacts connected in series with said coil of the station shutdown relay.

5. The combination of claim 4 in which said second control section of the circuit includes contacts actuated by additional compressor elements, said contacts being connected in series with the coil of a relay which has contacts connected in series with said station shutdown relay contacts and said coil of the engine shutdown relay.

References Cited in the file of this patent UNITED STATES PATENTS 1,524,076 Aikman Jan. 27, 1925 2,137,221 Aikman Nov. 22, 1938 2,390,650 Hollatz, et a1 Dec. 11, 1945 2,395,995 Dewey Mar. 5, 1946 2,402,187 Siver June 18, 1946 2,736,009 Barnickel Feb. 21, 1956 2,978,689 Tech et al. Apr. 4, 1961 

1. IN COMBINATION WITH A COMPRESSER STATION HAVING A PLURALITY OF INDEPENDENTLY COMPRESSOR UNITS, EACH OF WHICH INCLUDES A DRIVING HAVING A SHUTDOWN CONTROL, SAID STATION INCLUDING A PLURALITY OF NORMALLY FUNCTIONING STATION ELEMENTS, EACH OF SAID COMPRESSOR UNITS INCLUDING A PLURALITY OF NORMALLY FUNCTIONING COMPRESSOR ELEMENTS; AN AUTOMATIC CONTROL SYSTEM CONNECTED TO ALL OF SAID STATION AND COMPRESSOR ELEMENTS AND INCLUDING A FIRST CONTROL SECTION CONNECTED INDEPENDENTLY BETWEEN SAID STATION ELEMENTS AND THE SHUTDOWN CONTROL OF EACH OF SAID COMPRESSOR DRIVING ENGINES AND ACTUATED BY EACH OF SAID STATION ELEMENTS UPON A MALFUNCTION THEREOF TO SHUT DOWN ALL OF SAID COMPRESSOR UNITS AND A SECOND CONTROL SECTION CONNECTED BETWEEN ALL OF SAID COMPRESSOR ELEMENTS OF EACH COMPRESSOR UNIT AND THE SHUTDOWN CONTROL OF THE ENGINE THEREOF TO SHUT DOWN ONLY THE ENGINE THEREOF UPON THE MALFUNCTION OF ANY OF SAID COMPRESSOR ELEMENTS. 